Photonic networks on a silicon microelectronic chip offer the opportunity to overcome the power and bandwidth limitations in traditional microprocessor interconnects. One device for on-chip optical networks is a high-speed silicon electro-optic modulator.
All previous examples of silicon micrometer-scale modulators have been fabricated on single-crystalline silicon-on-insulator (SOI) wafers. The basic device structure is an optical resonator embedded in a diode. The diode is used to inject and extract charge from the resonator, which switches the light transmission on and off using the free carrier plasma dispersion effect.
Reliance on the SOI platform presents two difficult challenges for the integration of optics with microprocessor ships. First, crystalline SOI is the same material that electrical transistors are made from, and the large-scale integration of hundreds of optical devices required for an optical network would take a prohibitive amount of real estate away from transistors in the same silicon layer. Second, the buried oxide thickness in standard microelectronic SOI is much smaller than the optical wavelength and, therefore, not appropriate for a waveguide cladding.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.